1. Technical Field of the Invention
The present invention generally relates to a method for manufacturing an electro-optical device including an electro-optical panel having a pair of substrates, which have a predetermined size and are bonded to be opposite to each other, an electro-optical device manufactured by the method, and an electronic apparatus using the electro-optical device. More specifically, the present invention relates to a process for preventing the substrates from being cracked in the state of an electro-optical panel.
2. Description of the Related Art
Electro-optical devices, such as liquid crystal devices, LED (Light-Emitting Diode) display devices including organic electro-luminescence display devices, plasma display devices, FED (Field Emission display) devices, electrophoresis display devices, and DMDs (Digital Micro-mirror Devices), have a panel structure in which a pair of glass substrates, on which driving electrodes for driving an electro-optical material are formed, are bonded to each other by a sealing material or a panel structure in which protective glass substrates are bonded to a pair of glass substrates, on which electrodes for driving an electro-optical material are formed, by a sealing material. In the electro-optical devices having any one of the panel structures, substrates, which are cut out in a predetermined size from a large substrate, are used rather than single-sized substrates.
For example, in the liquid crystal device, electrode patterns are formed on a large substrate having a plurality of single-sized liquid crystal panels. After a plurality of large substrates are bonded to each other, the bonded substrate is cut into a predetermined size, thereby forming a single product liquid crystal panel.
In the liquid crystal panel, since it is necessary to provide liquid crystal-driving signals to driving electrodes, one of a pair of the substrates protrudes from an edge of the other. Substrate mounting terminals, to which a plastic substrate is connected, IC mounting terminals, on which an IC is mounted, and wiring lines for providing output signals from the IC to electrode patterns are formed on the protrusion region.
Substrates included in the liquid crystal panel are cut out into a predetermined size by a method, in which cut lines are drawn on a large substrate by a diamond cutter and then pushed and divided by the jig applying force from the rear side of the substrate, or by a method, in which cut lines are drawn on a large substrate, and then a laser is irradiated on the cut lines to divide the large substrate. However, in any one of the cutting methods, small scratches or cracks are made on the edge or the cut faces of the substrate by stress in the process of cutting the substrate, and those scratches or cracks are grown by additional stress. As a result, if a liquid crystal device is used in a mobile phone, a liquid crystal panel is broken by an impact when the mobile phone is dropped.
Therefore, the inventors propose that an etching step is performed on the edge or the cut face of the cut substrate to remove fine scratches or cracks.
However, since strong acid such as hydrofluoric acid is used to etch the glass substrate and wiring lines composed of an ITO film or a metal film are formed on the glass substrate, the wiring lines may be damaged by etching solution when fine scratches or cracks, which are made in the edge or the cut face of the glass substrate, are removed by etching.
Accordingly, it is an object of the present invention to solve the problems and to provide a method for manufacturing an electro-optical device capable of removing fine scratches or cracks on the edge or cut face of a substrate using an etching step without damaging wiring lines formed on the substrate, an electro-optical device manufactured by the method, and an electronic apparatus using the electro-optical device.